Structural board from wood waste, extracted flour of soya beans and melamine-urea formaldehyde resin



UNl'l-.. OFFICE STRUCTURAL BOARD FROM WOOD WASTE, EXTRACTED FLOUR OFSOYA BEANS AND MELAMINE-UREA FORMALDEHYDE RESIN Joseph N. Sears,Sacramento, Calif., assignor to L. J. Carr & 00., Sacramento, Calif., apartnership No Drawing. Application October 10, 1949, Serial No. 120,603

3 Claims, (Cl. 260--6) This invention is directed to, and it is anobject to provide, a novel dry-thermo pressed structural board, in sheetform, produced from woodwaste.

Another object of the invention is to provide a dry-thermo pressedstructural board whose principal constituents are wood-waste ground ormilled to a selected particle size, and a novel protein binder effectiveunder conditions of heat and pressure to bond the wood particles into astructural board having desirable characteristics with respect tosurface finish, density, and strength. The board is relativelywater-resistant; has good dimensional stability; and excellent fiexuraland impact strength due to high density.

A further object of the invention isto provide a dry-thermo pressedstructural board, as above, wherein the protein constituent is theextracted flour of soya beans; such protein being used as the primarybinder, and it is found to serve the purpose in an exceedingly effectivemanner even though present in small proportion relative to the reducedwood-waste.

An additional object of the invention is to provide a dry-thermo pressedstructural board which embodies, in addition to the reduced wood-wasteand protein binder, other initial constituents including a resin binder,a humectant and lubricator, a fire retai dam, and a fl ng Asdistinguishe F631 'dtirer pressed structural boards, the above fireretardant and fungicide are distributed uniformly throughout the board*rather than merely a surface application as is conventional.

A further object of the invention is to provide a dry-thermo pressedstructural board which is capable of ready and economical manufacture;the novel processing or method of production being relatively simple,and designed for mass production of the board.

It is also an object of the invention to provide a dry-thermo pressedstructural board in sheet form which can be sawed, machined, sanded, andotherwise handled in the same manner as wood, buthaving no grainis notsubject to splitting.

Still another object of the invention is to provide a practical,reliable, and convenient to use structural board, and one which will beexceedingly effective for the purpose for which it is de- Signed.

These objects are accomplished in the manner and by the method as willfully appear by a perusal of the following specification and claims.

Referring now more particularly to the details of the structural boardand the method of manufacturing thereof, a preferred or standard formulafor the same is as follows:

Per cent Reduced wood-waste 90.40 Solvent-extracted flour of soya beans5.00

? Melamine-urea formaldehyde 1.00 Ammonium phosphate 1.25 Ammoniumsulfate 1.25 Boric acid .75 Ethylene glycol .10 Pentachlorphenate .25

ject to some variation, as for example:

Per cent Reduced wood-waste 86.65

Solvent-extracted flour of soya beans 8.00

Melamine-urea formaldehyde 1.50

Ammonium phosphate 1.25

Ammonium sulfate 1.25

Boric acid .75

Ethylene glycol .10

, Pentachlorphenate .50

In the formula immediately above the protein and other ingredients,exclusive of the Woodwaste, remain however in relatively smallproportion to the latter.

The following is a more particular description of each of theingredients which comprise the formula:

i. RM.

The selected wood-waste can be the lumber production waste from all hardor soft wood operations, and the initial physical form of the wood-wastemay be sawdust, chips, shavings, blocks, or slabs. The selectedwood-waste is processed in quantity through an interplane' grinder orhammermill, with the resulting particle size subject to selectivecontrol. Where it is desired that the resultant structural board be verysmooth, with little or no flexibility, the wood waste is reduced to veryfine particles comparable to sanderdust or fine sawdust.

For a less smooth surface but a greater moisture resistance and greaterfiexural and impact strength, the wood-waste is hammermilled toapproximately /20 particle size.

Coarser wood-waste can be made into a structural board by the presentformula but the board, while having excellent fiexural and tensilestrength, has reduced dimensional stability and a rough surface.

The reduced wood-waste from an interplane grinder produces a Waste whichhas long fine fibers. This is desirable, as the long fiberswhen fed intoa matcause a heterogeneous arrangement with the fibers crossed severaltimes by other fibers. This fiber arrangement produces a structuralboard of highest possible moisture resistance, dimensional stability,tensile strength, and impact and flexural strength, as well as a uniformsmooth surface. It is therefore preferred that the reduced wood-waste beprocessed in a reduction apparatus which produces waste having theaforesaid long, fine fibers.

The protein in the formula serves as the primary binder, and suchprotein is the solvent extracted flour of soya beans. The solventextraction removes substantially all of the oil from the soya flour,without causing the meal to be heated to the excessive temperaturesrequired in the expelled meal process. The flour as used in the formulacontains approximately 60% protein, 5% moisture, 4% fiber; 1% oil, andorganic combinations of potassium, calcium, magnesium, sodium and iron.

The melamine-urea formaldehyde is a resin binder composed of one partmelamine to one part urea. These two chemicals are combined withformaldehyde and conventional plasticizers and are blended with the drpowdered resin. The melamine-urea formaldehyde serves the purpose of asecondary binder, being desirable because of its ability to flow duringthe thermopressing operation, and additionally imparts greater waterresistance and impact strength to the board.

The ammonium phosphate used is the secondary ammonium phosphate ordiammonium hydrogen phosphate (NH4) zHPOi. This salt is used inconjunction with the ammonium sulfate and boric acid for enhancing thefire resistant quality of the structural board.

The ammonium sulfate (NI-1029,04 is the inexpensive commercial grade andthe boric acid (or orthoboric acid) H3BO3 is also the commercial gradeof granular acid.

The ethylene glycol (HO.CI-I2.CH2OH) is used as a humectant andlubricator in the board formulation.

The sodium pentachlorphenate is a water soluble sodium salt ofpentachlorphenol which reacts with the acid carbon dioxide from the airto make a water insoluble and equally toxic pentachlorphenol. Thispentachlorphenol is very stable and serves in the board as a fungicide,giving resistance to organisms such as Cerwtostomella pilz'fera,Hormonema dematiodes, Fomes roseus, etc., as well as resistance torodent and termite damage or destruction.

The following steps are employed as the method of manufacture of thedry-thermo pressed structural board:

The selected wood-waste is milled in quantity and to a predeterminedparticle size, as heretofore described, in an interplane grinder orhammermill, and is then sprayed with a water mixture solution of theethylene glycol and sodium pentachlorphenate; the solution being sprayed4 onto the milled woodwaste at a calculated rate to bring the totalmoisture to 10-12% by weight.

The relativel dry, milled wood-waste is then blown into a cyclone whichhas a helicoid volumetric conveyor at the bottom thereof, the helicoidbeing set to deliver a volume of woodwaste equal to approximately 92% ofthe total required mix for the subsequent press cycle of the boardproduction. Following delivery from the helicoid the wood-waste isadmixed with the dry premixed chemicals (protein, plastic, phosphates,sulfate, and boric acid) in any suitable type of dry mixer.

From the dry mixer the total mixture is deposited on a conveyor and fedto a storage hopper.

The mixture is delivered from such storage hopper to a mechanical feederwhich is operative to feed the mixture in the form of a mat onto steelforming and pressing trays; such mechanical feeder including ahorizontal strike-off device which assures that the mat of the mixtureon the forming and pressing trays is of predetermined and uniformthickness. This is desirable so that the resultant board will haveuniform thickness throughout.

After the mat of the mixture has been placed on the forming and pressingtrays such mat is subjected-4n a press-to a platen pressure of5002500pounds per square inch for a period of approximately five minutesat a platen temperature of 280-290 F.

At the end of the pressing period the press is opened and the hotfinished structural boards are removed from the press and the trays. Theboards after cooling are trimmed to the desired size, packaged, andwarehoused.

The action or reaction of the protein binder with the milled wood-wasteunder the conditions of pressure and heat in the press is very complex,but the following is believed to be generally the chemistry of theprocess:

The amount of protein existent in the milled wood-waste is fortified orextended with the extra protein, such as flour of soya beans, introducedinto the mixture, and on the hydrolysis accomplished in the press theproteins give a mixture of amino acids and cause a bonding action, whichin turn results in the soluble protein becoming insoluble. The alkaloidsin the wood-Waste are, by this acid reaction, made soluble and are movedcloser to the surface of the board, making a very toxic outer shell onsaid board. Further, it has been found that the other organic acids(fatty and resin) in the wood react with the protein under theaccelerated heat and pressure conditions gained in the pressing cycle.This reaction also aids in accomplising the adhesive advantages of theprotein.

The employment of the protein as the primary binder results in theformation, under the conditions of heat and pressure in the press, of aboard having more desirable structural characteristics than wood-wasteboards produced with a plastic as the primary binder.

From the foregoing description it will be apparent that I have conceivedof an article of manufacture which will have the many advantages andwill satisfy the objectives as set forth in the preamble to thisspecification.

While this specification sets forth the present and preferred details ofthe structural board and the method of manufacture thereof, still inpractice such deviations from such detail may be resorted to as do notform a departure from the spirit of the invention, as defined by theappended claims.

Having thus described the invention the following is claimed as new anduseful, and upon which Letters Patent are desired:

1. A high density, dry-thermo pressed structural board including, asconstituents, a woodwaste milled to predetermined particle size, aprimary binder comprising a protein, and a substantially lesser amountof a resin binder; the wood-waste being present in a percentage greaterthan 80%, the protein binder being extracted flour of soya beans presentin a percentage less than 10%, and the resin binder being melamineureaformaldehyde present within a range of 1 /2 and 1%.

2. A high density, dry-thermo pressed structural board comprised of thefollowing in approximately the percentages stated: Reduced wood waste90.40%, extracted flour of soya beans 5.00%, melamine-urea formaldehyde1.00%, ammonium phosphate 1.25%; ammonium sulfate 1.25%, boric acid375%, ethylene glycol .10%, and pentachlorphenate .25

3. A high density, dry-thermo pressed structural board comprised of thefollowing in approximately the percentages stated: Reduced wood-waste86.65%, extracted flour of soya beans 8.00%, melamine-urea formaldehyde1.60%, am-

6 monium phosphate 1.25%, ammonium sulfate 1.25%, boric acid .'75%,ethylene glycol 10%, and pentachlorphenate .50

JOSEPH N. SEARS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,007,585 Satow July 9, 1935 2,034,522 Loetscher Mar. 1'7,1936 2,038,113 Irey Apr. 21, 1936 2,143,413 Ellis Jan. 10, 19392,185,333 Denman Jan. 2, 1940 2,315,402 DAlelio Mar. 30, 1943 2,338,710Dodge Jan. 11, 1944 2,368,660 Hochstetter Feb. 6, 1945 2,436,329 PorterFeb. 1'7, 1948 2,446,304 Roman Aug. 3, 1948 2,452,054 Jones et a1 Oct.26, 1948 2,578,489 Roman Dec. 11, 1951 FOREIGN PATENTS Number CountryDate 480,316 Great Britain Feb, 1'7, 1938 OTHER REFERENCES Winton, TheStructure and Composition of Foods, vol. I, 1932 page 516.

1. A HIGH DENSITY, DRY-THEREMO PRESSED STRUCTURAL BOARD INCLUDING, ASCONSTITUENTS, A WOODWASTE MILLED TO PREDETERMINED PARTICLE SIZE, APRIMARY BINDER COMPRISING A PROTEIN, AND A SUBSTANTIALLY LESSER AMOUNTOF A RESIN BINDER; THE WOOD-WASTE BEING PRESENT IN A PERCENTAGE GREATERTHAN 80%, THE PROTEIN BINDER BEING EXTRACTED FLOUR OF SOYA BEANS PRESENTINA PERCENTAGE LESS THAN 10%, AND THE RESIN BINDER BEING MELAMINEUREAFORMALDEHYDE PRESENT WITHIN A RANGE OF 1 1/2 AND 1%.